Five elephants were found dead in a massive pit in woodland in Thailand.

The family of jumbos - two adults, one younger elephant, and two babies - were estimated to have been dead for at least two months when they were found by foraging locals in Lam Khlong Gnu National Forest Reserve in Kanchanaburi province, on May 6.

Their bodies were submerged in a muddy sludge under the pit, where their flesh had already dissolved and mixed in with the water, turning it into a dark slime.

Upon initial investigation, park officers found that the elephants might have been feeding in the area when the ground collapsed from the weakened surface where there used to be an underground morning tunnel.

National park head Pichet Chaisawat said: ‘The villagers who entered the forest called us when they found the animals. The hole where they have fallen into were above a tunnel for an abandoned mining site. We sent a team to inspect the area and interview the village chief.’

The decomposing bodies were pulled from the pit and sent back to their facility for research while the hole would be filled with soil to avoid similar incidents from happening again.

Aside from filling in the sinkhole, the village chief promised to add a barrier and warning signs in the area to keep people and animals away from the underground tunnels.